Glycated haemoglobin--a marker and predictor of cardiovascular disease

Abstract

Glycated haemoglobin is formed by simple chemical reaction between haemoglobin and blood glucose. It represents a reliable and moving average of blood glucose over preceding three months. In 2009 the International Expert Committee recommended the use of HbA1c to diagnose diabetes with a cut-off of 6.5%. Studies have shown that HbA1c even in the range of 5.5% to 6.5% poses considerably high risk of morbidity and mortality due to cardiovascular disease. HbA1c as a test is important because about 220 million people have diabetes and with increasing life expectancy and emergence of type 2 diabetes in children makes it even more important. Each 1% increase in HbA1c poses 15-18% relative risk of cardiovascular disease in T1DM and T2DM respectively. CVD is a major cause of death and disability among diabetes patients and glycated haemoglobin itself is proportionately linked with excess CV morbidity and mortality. UKPDS-35 demonstrated 14% reduction in the incidence of acute myocardial infarction with only 1% reduction in HbA1c in T2DM patients. The DCCT reported significant reduction in retinopathy and nephropathy in T1DM, the follow up trial EDIC demonstrated 42% reduction in CVD with intensive reduction of HbAlc. This review is written to remind ourselves of the importance of this simple test which can predict early CV mortality in patients without prior CVD and poor prognosis in established cardiovascular disease. In a country like ours, Pakistan; where diabetes is prevalent with poor health awareness and limited resources, a test like HbA1c which costs Rs, 500.00 twice a year should be considered a cost effective way to avoid the long term diabetes complications, which once start unfolding put enormous burden on already stretched healthcare resources which could easily be avoided by intensive control of diabetes.